1. Field of the Invention
The present invention is related to a method and apparatus for corrugating a flat material, such as a printed web in a folding apparatus assigned to a rotary printing press.
2. State of the Art
U.S. Pat. No. 5,029,842 relates to signature handling apparatus having a first conveyor which sequentially moves signatures to a discharge station. At the discharge station, the signatures are sequentially transferred to a receiving conveyor. A corrugator assembly is located at the discharge station to stiffen the signatures by forming corrugations which extend between leading and trailing end portions of the signatures. Although the corrugations are only temporarily maintained in the signature, the corrugator assembly is close enough to the receiving conveyor that a corrugation is maintained as a leading end portion of the signature moves to the receiving conveyor. Thus, the corrugator assembly is spaced from the receiving conveyor by a distance which is less than the distance between the leading and trailing end portion of the signatures.
U.S. Pat. No. 5,107,733 relates to an apparatus for cutting and transporting a paper web in a folding apparatus of a printing press. The apparatus includes a pair of cutting cylinders for cutting web sections from the web, and a transporting device for transporting the web sections away from the cutting cylinders. The first cutting cylinder has at least one cutting anvil, and the second cutting cylinder has at least one cutting knife which meets the cutting anvil at a nip between the cutting cylinders to cut the web moving through the nip. A plurality of strips are supported on the first cutting cylinder and a plurality of strips are supported on the second cutting cylinder. The strips have positions on the cutting cylinders at which they impress a temporary reinforcing profile onto each newly formed leading portion of the web, when the strips move through the nip. At least one smoothing surface is also supported on the first cutting cylinder and at least one smoothing surface is also supported on the second cutting cylinder. The smoothing surfaces have positions on the cutting cylinders, wherein the smoothing surfaces remove the temporary reinforcing profile from the leading portion of the web when the smoothing surfaces move through the nip.
The above-mentioned approaches impose a corrugated profile in order to stiffen the leading edge of a ribbon, web or signature by corrugating the ribbon, web, or signature with rollers having opposing large and small diameter sections. The roller surfaces can be steel brushes, Velcro-tape, or urethane, and must contact the ribbon, web or signature. This causes the roller surfaces to wear and can cause marking of the ribbon, or web signature. Different materials have consequently been used to prolong the life of the various roller components, although wear of these components still occurs.
Known corrugating methods also have a large sensitivity to position adjustments, and different designs have been developed in an effort to reduce the sensitivity of the position adjustments. Furthermore, known methods of corrugating induce corrugation locally, such that the corrugation effect must be projected to the location where it is required. Accordingly, it would be desirable to improve the corrugation of a flat material, such as a ribbon, web or signature.